Apr 3, 2009 - 6 months, nocturnal sleep is extended and becomes more ... goal of a reasonably consolidated sleep during the night. However ... let the event run its course, or alternatively, to wake up the ... worsens over time. Even mildly enlarged

Nutrition in Clinical Practice

Oct 5, 2011 - lars out of pocket to treat illness or improve health in gen- eral.7,8 In 2007, 25% of U.S. ... nonprescription dietary supplements.12 Worse still is that users and nonusers of ...... Supplement Health and. Education Act of 1994.

Obesity is a global public health issue. Although the etiology of this global epidemic is multifactorial, most sufferers would be delighted to find a relatively effortless way to lose weight. Herbal “weight loss pills” can fit the bill. The authors systematically review the scientific evidence concerning various weight loss agents that are available over the counter or in food stores. The review provides a starting point to make informed choices

besity is now recognized as a pathological condition, one that has a direct effect on morbidity and mortality. One-third of the adult American population is now obese (age-adjusted prevalence of obesity being 33.8% in 2007–2008), and another third is overweight, for a combined prevalence of 68%.1 The epidemic of obesity is expanding worldwide, which makes obesity a global public health problem.2 Although the etiology of this global epidemic is multifactorial,2-5 most individuals afflicted by this condition would be delighted to find a relatively effortless way to lose weight. Alternative medicines have been used worldwide for many years to treat illness or promote health.6 Health services such as massage therapy, acupuncture, chiropractic care, and natural and herbal products can all be defined as alternative therapy. Americans are spending billions of dollars out of pocket to treat illness or improve health in general.7,8 In 2007, 25% of U.S. adults reported using different forms of complementary and alternative medicine (CAM) for health promotion, whereas an additional 17% reported using it for treating an illness.6 Surveys consistently show that nutraceutical supplements (vitamins and herbs) and

unconventional methods are the most common forms of CAM used in the United States.8-10 Although use of complementary therapy and alternative medicine is low in those who are obese,11 recent data on the use of dietary supplements for weight loss suggest that more than 30% of those who have attempted serious weight loss have used nonprescription dietary supplements.12 Worse still is that users and nonusers of dietary supplements assume that these supplements have been evaluated for safety and efficacy.12 In reality, few scientifically rigorous studies have been conducted to assess the efficacy of the various agents touted as useful, and anecdotal stories of efficacy are marred by selection bias, exaggerations, and folklore. The limited clinical trials and case reports are widely scattered in the medical literature, making it difficult to compile them and reach a valid conclusion regarding the effects. The material that follows details what has been published regarding most of the botanically derived agents that have any data to support possible efficacy.

Dietary Fiber Dietary fiber intake is associated with a plethora of health benefits, including reduced risk of developing coronary heart disease, hypertension, stroke, and dyslipidemias.13 In addition, high intake of dietary fiber is associated with improved insulin sensitivity and may aid in weight loss and weight maintenance among obese individuals.13 However, data on dietary fiber intake in Americans indicate that Americans are far from consuming the recommended levels (25 g/d for adult women; 38 g/d for adult

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

540 Nutrition in Clinical Practice / Vol. 26, No. 5, October 2011

men) of fiber.13 This is likely because American diets lack adequate amounts of whole-grain foods, fruits, vegetables, and legumes,14-16 which are associated with high fiber intake, low energy density, and high nutrient density.17-20 Moreover, high fiber intake has been associated with lower body mass index (BMI) and enhanced weight loss and weight maintenance.19,20,22-24 Thus, dietary fiber supplements may provide adjunctive benefit for weight loss/weight maintenance in those seeking to lose weight. Fibers are also classified as dietary fibers, which consist of intrinsic and intact carbohydrates in plants, and functional fibers, which consist of carbohydrates that have a beneficial physiological effect in humans.25,26 All types of fibers are essentially nondigestible by the human gut, although they may be acted upon by gut microflora.25,26 In simple terms, fibers are classified as soluble or fermentable fibers and insoluble fibers, which can be fermented by gut microflora and provide bulk.25,26 Soluble fibers are natural gel-forming fibers such as pectin, gum, and mucilage, and insoluble fibers are structural fibers such as cellulose, lignin, and some hemicellulose.25,26 Fibers are components of a healthful diet and add bulk,25,26 thereby decreasing the energy density of foods.17-21 Insoluble fiber has been shown to decrease subjective appetite and thereby food intake.27 Soluble fibers exert a hygroscopic effect, by which they slow absorption of energy-dense macronutrients. A fiberrich diet has been shown to provide high satiety compared to a low-fiber diet.28 These effects have been observed both during a meal and between meals.28

Psyllium Psyllium, one of the water-soluble fibers, is derived from blonde psyllium seeds; it ferments slowly, helps build up fecal mass,29 and is commonly available over the counter as a laxative.30 Several studies have shown that psyllium supplementation may lower or improve risk factors that are associated with the development of cardiovascular diseases and diabetes, including obesity.31-37 Psyllium supplementation (up to 3.5 g per meal) may have significant beneficial effects on body composition changes in obese individuals, which include BMI and waist circumference, while causing minimal or no abdominal discomfort.31-33 Some data from randomized clinical trials indicate that psyllium supplementation at doses higher than 3.5 g per meal does not have these effects on body composition in obese individuals, but improvements in metabolic risk factors are still evident.35 However, higher doses of psyllium and overall fiber intake per meal (>3.5 g per meal) are associated with significant abdominal discomfort.34,35 Although some observations support the role of psyllium in treating obesity,31-34 inconsistency in data makes it difficult to draw definitive conclusions.35 Still, we can definitely conclude that psyllium has beneficial effects on risk factors associated with the development of cardiovascular diseases.36-38

Konjac Root Fiber Konjac is a plant local to Asian countries, especially India, Japan, and Korea. It contains glucomannan, which is a fermentable, highly viscous dietary fiber. This fiber has been shown to assist in weight loss and improve lipid profile.39,40 Walsh et al40 reported that glucomannan 1 g 3 times a day produced significant weight loss (~5.5 lbs) in obese individuals without any adverse effects. In contrast, 1 study that used a combination of psyllium (3 g/d) and glucomannan (1 g/d) showed no effect on body weight but found hypolipidemic effects.34 Konjac root fiber may have beneficial effects on improving metabolic parameters41-43 and may produce modest weight loss, but larger clinical trials are needed. Studies that found an effect of glucomannan alone were had small sample sizes (n = 20–30).40-43 No adverse events or abdominal discomfort have been reported with the use of this fiber supplement in amounts ranging from 3–4 g/d.40-43 However, its use in those seeking weight loss is inconclusive, and more research with body weight as a primary end point is warranted.

Chitin Chitin is component of crab, shrimp, and lobster shells and thus abundantly available in nature.44 Like dietary fiber, chitin is a polysaccharide that is indigestible by the human gut. Chitosan is deacetylated chitin. In rats, chitosan has been shown to decrease hepatic cholesterol and increase bile acid and fat excretion.45 In contrast, in humans, a combination of chitosan and glucomannan seems to decrease serum cholesterol (via fecal steroid excretion but not fat excretion).46 The exact mechanism of action is not well understood; however, it has been shown that negatively charged lipid molecules avidly bind to the positively charged tertiary anion group of chitosan polysaccharide, and this decreases absorption.46,47 There are not sufficient human studies to prove a beneficial effect of chitosan for weight loss. One metaanalysis reviewed 14 studies that tested the effect of chitosan on weight loss and concluded that it causes a small net effect of approximately 1.7 kg.48 Furthermore, results from the high-quality clinical trials reviewed were clinically insignificant (–0.6-kg weight loss) compared with those from lower quality studies (–2.3-kg weight loss), further suggesting that chitosan may not be effective for weight loss.48 Overall, human studies have yielded mixed results,48,49 having been conducted on a small scale and over a short duration.50 Moreover, many studies of chitosan show that it is ineffective for weight loss.51-55 Only 1 study was found that reported significant improvements in body composition with chitosan supplementation (3 g/d) in overweight adults.56 In sum, studies suggest that chitin/chitosan probably has some weight reduction and cholesterol-lowering effects, but these effects are not clinically significant at reasonable doses (3–6 g/d).51-55

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

Nutraceutical Supplements for Weight Loss / Poddar et al 541

Guar Gum Guar gum is derived from the Indian cluster bean (Cyamopsis tetragonolobus) and is known to exert its action via imparting postprandial fullness and increasing bowel viscosity, which in turn may result in reduced appetite, lower food intake, and improved satiety.57-60 Reduced appetite and higher satiety may have an impact on weight loss in obese individuals via lower energy intake; however, evidence from studies on the effects of guar gum supplementation indicate that it may not help in weight loss.57,61 One meta-analysis of randomized controlled trials concluded that it had no significant effects on weight changes in obese individuals.61 Since the meta-analysis, only 1 study has been identified that tested the effect of guar gum on body weight.59 However, this study did not include weight as a primary measure and concluded that guar gum supplementation had an effect on satiety but did not result in changes in body weight.59 In summary, studies on dietary fiber supplements do not provide strong evidence that they may support weight loss. The purported mechanism via which they may induce weight loss includes increased satiety, reduced appetite, and blockage of dietary fat absorption. Although some gastrointestinal discomfort/bloating may accompany acute increases in extract-based or dietary fiber intake, in general, fiber supplementation does not entail significant adverse effects. Dietary fiber is one alternative medicine that can be obtained from a wisely chosen regular diet. When needed, supplements are readily available in supermarkets and pharmacies over the counter.

Garcinia cambogia (Rind of Brindell Berry) Garcinia cambogia is native to Southeast Asia. It has been proposed that hydroxycitric acid (HCA), the active ingredient in G cambogia, competitively inhibits adenosine triphosphate–citrate lyase, an extra-mitochondrial enzyme that may inhibit de novo lipogenesis and reduce appetite in some in vivo studies.62 However, evidence of a positive effect of G cambogia as a weight loss agent is lacking.63-65 One study evaluated the efficacy of this compound (1500 mg/d) on weight and body fat loss in overweight participants and concluded that it did not produce significant changes in the intervention group beyond that seen in the placebo group.63 Preuss et al66 demonstrated weight loss efficacy of this compound but found that the results were better when it was administered in combination with other active agents. One other study showed that supplementation with HCA did not alter fat oxidation and energy expenditure,67 thus reporting conflicting results in comparison to studies that support the role of HCA in fat oxidation.68 More research is warranted regarding the role of this compound in weight loss. One review evaluated the safety of G cambogia and reported no significant health hazards69 vs

another study that did report adverse events.63 In summary, HCA decreases fatty acid synthesis and reduces appetite, but further data in humans are needed to determine its role in weight loss. Evidence on safety and efficacy of the compound is vague, and at this point, no conclusion can be drawn. One needs to use caution before recommending and/or using it as a weight loss agent.

Conjugated Linoleic Acids Conjugated linoleic acids (CLAs) are positional and geometric isomers of linoleic acid, a polyunsaturated fatty acid. CLAs are available in the trans and, more abundantly, in the cis form in meat and dairy products. Several studies have been conducted using in vivo and in vitro models to assess the effect of CLA in cancer, diabetes mellitus, atherosclerosis, immune modulation, and possibly weight loss.70,71 Although these studies have shown health benefits in the in vivo and in vitro models,70 there is lack of enough evidence to support these health benefits in humans.71 Various mechanisms of action have been proposed via which CLA isomers may exert the effect on weight loss in animal models.72-76 In general, they reduce fat synthesis and increase oxidation. However, human trials with CLA provide weak or no evidence to support the role of this compound in the treatment of obesity with varying conclusions.77-82 These results make it difficult to understand the definitive role of CLA on body composition changes in humans. A meta-analysis performed of 18 human studies reached the conclusion that CLAs do possess a beneficial effect on body composition, which, although modest, may play an important role cumulatively over time.80 Although data from in vitro and in vivo studies provide strong support for the role of CLA in weight loss, evidence from human studies has led to conflicting results, suggesting a need for further research.

Teas (Camellia sinensis) Camellia sinensis, the tea plant, is native to southwest China and is grown on a large scale in various tropical countries.83 The processing of tea leaves leads to 3 different types of teas—namely, green tea (20% is produced worldwide and mainly consumed in Asian countries), black tea (78% is produced worldwide and is consumed by Western countries), and oolong tea (2% is produced worldwide and is consumed in southern China).83 All 3 types of teas are brewed differently and undergo partial fermentation and oxidation processes and possess different percentages of polyphenols called catechins.83 Green tea undergoes minimal oxidation and is steamed soon after harvesting to prevent further oxidation. Oolong tea has oxidation levels between green tea and black tea.

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

542 Nutrition in Clinical Practice / Vol. 26, No. 5, October 2011

Black tea is completely oxidized tea and is very popular in some parts of Asia, such as India, and in Africa.83 Teas are perhaps the most widely used alternative medicinal agents. They are inexpensive, are readily available, and have a large spectrum of positive health effects ranging from antioxidative, anticarcinogenic, antidiabetogenic, and antiobesogenic properties.83 Teas are becoming popular for potential benefits in preventing cardiovascular risk factors and longevity as well.83 Health benefits associated with tea consumption are mainly attributed to the polyphenolic compounds called catechins present in them.83 These health benefits depend on the amount of tea consumed along with the type of tea and the bioavailability of the catechins.83 Although different teas are associated with different health benefits, for the purpose of the current review, the role of green tea in the prevention of weight gain will be discussed.

Green Tea The main active polyphenolic compounds found in green tea preparations are (–)-catechin gallate (CG), (–)-gallocatechin gallate (GCG), (–)-epicatechin gallate (ECG), and (–)-epigallocatechin gallate (EGCG); caffeine; proanthocyanidins; and flavonols (myricetin, caempherol, quercetin).84 Green tea has been evaluated in multiple clinical trials for cancer-protective, cardioprotective, antioxidant, and weight loss effects. Although a detailed discussion of its non-weight-related effects is beyond the scope of this article, green tea has been evaluated for and shown to have convincing anticancer effects85-88 and can help prevent the metabolic syndrome by a cholesterol-lowering effect.89 The results related to weight control benefits are more mixed, although multiple studies have shown that catechin-rich (>500 mg/d) green tea significantly reduces body weight and fat.90-94 Researchers have postulated that the active ingredients in green tea help achieve weight reduction via several possible mechanisms: increase in energy expenditure, fat oxidation, and suppression of the lipogenic enzyme fatty acid synthetase, thereby inhibiting lipogenesis.95 It has also been postulated that caffeine in tea may act synergistically with catechins to increase fat oxidation and energy expenditure. In addition, green tea catechins may upregulate enzymes involved in hepatic fat oxidation.95 A recent meta-analysis of 11 clinical trials concluded that catechin-caffeine mixtures may have a small positive effect on weight maintenance via fat oxidation and thermogenesis.96 The magnitude of the effect may vary based on race and level of habitual tea intake.96 However, at least 2 clinical trials contradict these abovementioned conclusions.97,98 One study suggested that low habitual intake of catechin from green tea and caffeine together (270 mg green tea catechin and 150 mg caffeine per day) may assist in weight maintenance after weight loss.99 Caffeine is another constituent of green tea83,84

that has been evaluated for weight loss and is postulated to increase energy expenditure independently.100 These ingredients may work synergistically to effect weight loss. Two studies have been performed with oolong tea as a long-term adjunct for weight reduction; its effect is likely due to its similar active ingredients and same mechanisms of action as green tea.101,102 There are no known adverse effects of green tea and other teas, and they may serve as an adjunct therapy for weight loss.

Caffeine Caffeine is the main active ingredient of the most commonly consumed beverages in the world—namely, coffee, tea, and caffeine-containing drinks that include sodas and sports and energy drinks.103 Caffeine content varies in all these beverages, with the highest being in teas and coffee, in which it is present naturally.103 Variability in the amount of caffeine present in coffee and tea also is dependent on the environmental conditions, such as how it is grown and brewed. On average, 100 mg of caffeine is present in one 8-oz cup of coffee.103 Caffeine is known to have varied health effects in humans. It is generally known as a central nervous system stimulant. It is known to enhance mood, increase alertness, and improve exercise performance.103 Its use in weight control has been evaluated primarily in combination with the catechins in green tea96,99,104 and with ephedrine.105 One study assessed the effect of caffeine intake on body weight in a 12-year prospective study and concluded that an increase in caffeine intake led to reduced weight gain over a period.106 In contrast, a meta-analysis showed that caffeine and catechins together, and not caffeine alone, produce modestly significant reductions in body weight, waist circumference, and BMI.104 A similar double-blind placebocontrolled study showed that caffeine (200 mg/3 times a day) along with ephedra (20 mg/3 times a day) was effective in reducing body weight.105 One study examined the effect of habitual caffeine intake on body weight of obese individuals and concluded that caffeine intake is associated with modest weight loss via thermogenesis and fat oxidation, and habitual low caffeine consumption is associated with weight maintenance.96 However, most of the studies conducted in humans with caffeine are in combination with teas and/or ephedra, making it difficult to draw the exact conclusion that caffeine consumption may have on weight loss. Various mechanisms have been proposed to explain caffeine-induced weight loss. One of them is thermogenesis. Caffeine consumption has been shown to increase the energy expenditure by about 150 kcal in lean subjects and 79 kcal in obese subjects, thereby playing significant role in weight loss.107 Energy expenditure was found to be elevated for several hours after the caffeine intake (as

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

Nutraceutical Supplements for Weight Loss / Poddar et al 543

ground caffeinated coffee),100 whereas decaffeinated coffee did not have any such thermogenic effect.108 Caffeine also causes oxidation of fat, thereby stimulating the metabolic rate, thus making lipolysis a mechanism of weight loss.109 However, greater fat oxidation and lipolysis are evident in normal-weight individuals as compared to obese individuals.109 Caffeine has been shown to increase epinephrine in humans, thereby increasing lipolysis.110 These findings indicate that caffeine, when consumed in a limited amount (300 mg/d), including tremors, insomnia, and dizziness.105 The results from the studies on the effect of coffee on weight loss need to be interpreted cautiously as caffeine alone does not seem to be effective in moderate doses (300 mg/d) intake, which may show beneficial effects on weight loss. However, this adds to calories in the diet, which in turn may negate its effect.103

L-Carnitine L-carnitine is a compound that is involved in fatty acid metabolism and helps to transport fatty acids within the mitochondrial matrix, thus helping in oxidation of fat stores.111 Red meat, fish, poultry, and milk are food sources of L-carnitine, but our body can produce it endogenously as needed in the muscles.111,112 In recent years, a lot of research has focused on its potential use as a dietary supplement to treat obesity, angina, and heart failure.111,112 It is being studied for its potential use in improving exercise performance in athletes and reducing fatigue because it is a component of muscles and aids in fat metabolism.111-113 In normal healthy adults, L-carnitine supplementation (1 g/3 times a day) has shown to significantly increase fatty acid oxidation,114 suggesting it may help in weight loss.115 One animal study showed that indeed fatty acid oxidation reduces diet-induced obesity,116 which has been further corroborated in obese humans.117,118 However, a few animal119-122 and human studies123-125 that examined the effect of L-carnitine supplementation on body composition in obesity have concluded that it has no significant effect on body weight loss. One clinical trial in obese individuals reported an increase in fatty acid oxidation after L-carnitine (3 g/d) supplementation, but no changes in body composition

were present.123 Similarly, 1 study examined the effect of L-carnitine supplementation in overweight/obese individuals and concluded that it did not aid in weight loss.124 However, the study included bipolar individuals who had gained significant weight after a medicine that was administered for its treatment. The L-carnitine doses were at 15 mg/kg/d for 26 weeks.124 Villani et al125 examined the effect of L-carnitine (4 g/d) on weight loss in obese individuals for 8 weeks and concluded that it did not promote fat/weight loss in obese individuals. No adverse effects were reported.125 Only 1 animal study reported a significant effect of L-carnitine on weight loss in obese cats.126 These results do not support the role of L-carnitine in weight loss for obese individuals. It may be useful for athletes to improve exercise performance,113 but to recommend this compound as a potential weight loss supplement needs more research evidence. There is no evidence of any adverse effects of L-carnitine supplementation.112,127 Rubin et al127 examined the safety of supplementing 3 g/d of carnitine in healthy adults and determined that it posed no harm in healthy adults.

Ephedra sinica (Ma Huang) Ma huang is a Chinese folk medicine used for thousands of years for a wide variety of ills and conditions, including hay fever, asthma, and headaches, to name a few. China, India, and Pakistan are some of the suppliers of this herb. Usually, the dried green stems of the plant are boiled in water and served as hot tea, with doses varying from 1.5–9 g of the herb.128 Ephedrine is the major alkaloid found in the herb besides 6 others and ranges from 30%–90%. The active chemicals, ephedrine and pseudoephedrine, act as a sympathomimetic agonist and exert therapeutic effects that include central nervous system and cardiac stimulation in addition to other effects. These effects are purported to aid in weight loss and enhance endurance training.128 In recent years, ephedra has been mainly marketed in the United States as a weight loss adjunct and supplement to improve athlete performance.128 Ephedra exerts short-term as well as long-term effects on the autonomic nervous system, increasing sympathetic activity and impairing parasympathetic responses.129,130 It also promotes release of endogenous catecholamines.130 In animal studies, ephedrine has been shown to activate β-adrenergic receptors and thereby stimulate thermogenesis in brown adipose tissue.130 In humans, in addition to promoting thermogenesis in skeletal muscle,131 ephedrine tends to slow gastric emptying, thereby affecting food intake and satiety132 and acting as a weight loss agent. Certain chemicals have been shown to act synergistically or additively to enhance the weight loss effect of ephedrine. These include methylxanthines such as caffeine105 and aspirin.133 Several studies have

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

Some clinical data suggest that it may have weight loss effects. More data are needed. No evidence suggesting it aids weight loss. c Inconsistent clinical data suggesting it aids weight loss. d Strong evidence but safety issues and thus should be discouraged. e No evidence and safety concerns and thus should be strongly discouraged. b

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

Nutraceutical Supplements for Weight Loss / Poddar et al 545

shown positive effects of ephedrine with caffeine on weight loss.105,134-136 However, these effects have been observed in conjunction with reports of several adverse events. One review of 5 randomized clinical trials concluded that the benefits associated with ephedra/caffeine intake outweighed the risks,137 but a meta-analysis on the efficacy and safety of this compound indicated that its use is associated with 2.2- to 3.6-fold increase in adverse events.138 It has been reported that ephedra/ephedrine use is linked with psychiatric, autonomic, and gastrointestinal symptoms along with heart palpitations.105,134-138 The nature of the pharmacological effects of ephedra resulted in the Food and Drug Administration (FDA) banning its use in April 2004.139

Germander (Teucrium) Germanders, plants of the mint family that are found worldwide, traditionally have been used as a weight loss remedy, especially in Europe. They are also used for gout. Unfortunately, multiple care reports and case series have been published describing hepatotoxicity related to this herb.140 France banned germander after an epidemic of hepatitis caused by a germander powder-containing capsule that was marketed as an adjunct for weight loss.140,141 The hepatotoxicity of germander has been reproduced and studied in mice. These studies put an end to recommendations of germander as a weight loss adjunct.142,143

Capsaicin Capsaicin is a compound that is synthesized from the placenta of chili peppers, which are eaten worldwide. It is being widely studied for its potential role as an analgesic, anticancer, antioxidant, and antiobesity agent.144 Some evidence in the literature supports the role of capsaicin from chili peppers in reducing weight/fat mass in obesity.145-148 One double-blind randomized placebocontrolled trial showed that capsaicin supplementation in obese individuals resulted in weight loss, which correlated with decreased abdominal adiposity and high fat oxidation. Weight change and abdominal fat loss were higher in the capsinoid group (weight loss, –0.9 kg; abdominal fat loss, –1.11) vs the placebo group (weight loss, 0.5 kg; abdominal fat loss, –0.18) over 12 weeks of supplementation.145 The study reported that 6 mg/d of capsaicin supplementation when administered orally was safe and well tolerated by individuals.145 Capsinoids, nonpungent analogs of capsaicin, have been shown to increase adrenergic activity, energy expenditure, and fat oxidation at rest, suggesting its usefulness in weight loss.146 In addition, capsinoids have also been shown to increase satiety and reduce energy and fat intake.146,147 A recent study

revealed that ingestion of red chili increased energy expenditure and core body temperature, as well as lowered appetite, although prolonged intake may result in desensitization to this effect.148 Similarly, Belza et al149 reported that capsaicin along with caffeine and catechins had the potential to promote thermogenesis, resulting in body fat loss. Mechanisms involved in the weight loss effect of capsaicin include alteration of proteins involved in lipid metabolism and thermogenesis in the white adipose tissues.150 Overall, these results suggest that capsaicin may have an effect on weight loss via altering fat metabolism and increasing thermogenesis. Also, it is important to note that capsaicin supplementation may be necessary as compared to consuming chili peppers to achieve the benefits that are discussed. However, more studies are needed with this promising compound found in peppers.

Traditional Plants/Herbs Hoodia gordonii Hoodia is a plant indigenous to South Africa and Namibia. It is used locally as an appetite suppressant, famously by male tribesman while on prolonged hunting excursions. P57 is the active steroid glycoside present in Hoodia. P57 is thought to suppress appetite through central nervous system pathways.151 Animal studies indicate that P57 increases the production and/or content of adenosine triphosphate (ATP) in hypothalamic neurons and decreases food intake by 50%–60% for 24 hours after intravenous injection.152 Results from 1 double-blind placebo-controlled unpublished study indicate it may assist in weight loss.153 No published human trials have been conducted so far to evaluate the proposed mechanism of action and use of this agent for weight loss.

Cissus quadrangularis L. Cissus quadrangularis, commonly known as Veldt Grape or Devil’s Backbone, is a succulent vine native to West Africa and Southeast Asia. It has been used in traditional African and Ayurvedic medicine, and its use in the treatment of infections, cardiovascular issues, and nervous system disorders has been studied to some extent.154-156 Recently, its role in reducing body weight has been attracting attention.157-159 Some evidence suggests that C quadrangularis supplementation may help in reducing body weight, fat, and waist circumference along with markers associated with metabolic syndrome.157,158 Oxidative stress is a common feature that is associated with obesity, and this compound may help in reducing oxidative stress, as demonstrated in an in vitro model, along with improving body composition measures while

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

546 Nutrition in Clinical Practice / Vol. 26, No. 5, October 2011

reducing cardiovascular risk factors.159 Although these results provide some evidence in support of the use of C quadrangularis as a weight loss supplement, the studies were conducted by 1 group alone. Duplication of these results by other groups is needed to provide stronger support in favor of this compound in the use of weight loss. There is no evidence of any adverse events by this compound.

Citrus aurantium L. The unripe fruit of Citrus aurantium (bitter orange) has been used for centuries in traditional Chinese medicine. Recently, extracts have become popular in obesity treatment as an alternative to the banned ephedrine alkaloids.160 C aurantium contains the alkaloid synephrine and various phytochemicals and acts as an adrenergic agonist. It has been used clinically as a decongestant, as a vasopressor during surgical procedures, and for pupil dilations.160 C aurantium has physiological effects that are similar to ephedra, and the purported mechanism of action includes decreased gastric motility and thus early satiety and lower intake of food.160 Limited human studies have been conducted with this compound with conflicting results regarding effectiveness for weight control.161-163 In animal studies, the essential oil of Citrus aurantifolia led to a decrease in body weight and food consumption in mice.164 There are some safety concerns, similar to the concerns with ephedra; bitter orange has been listed by Consumer Reports165 as being possibly unsafe and a dietary supplement “to avoid.”

Trigonella foenum-graecum L. Fenugreek (Trigonella foenum-graecum L.) is an herbaceous annual plant belonging to the Leguminosae family that is cultivated in Mediterranean countries, Africa, and India. Fenugreek seeds have long been traditionally used for treating diabetes mellitus and other metabolic and nutritive conditions. The physiological effects of fenugreek seeds can be attributed to its fiber and high saponin content.166 Fenugreek has been previously reported to significantly reduce fasting blood sugar and improve glucose tolerance,167,168 reduce oxidative stress,169,170 improve the lipid profile, and reduce body weight171 in animal models. It has also shown immunomodulatory effects in animal models.172 In humans, it has been shown to significantly reduce fasting blood sugar and improve the glucose tolerance test in patients with type 1 diabetes mellitus173 and improve the lipid profile, insulin sensitivity, and glucose control in individuals with type 2 diabetes mellitus.174,175 Although no studies in humans have examined the effects of fenugreek seeds on body weight, studies in overweight and healthy individuals indicate that there is a significant decrease in dietary fat consumption and subsequent energy

intake with supplementation of fenugreek seed extract in quantities of >1000 mg/d.176,177 Additional studies in humans are needed to draw conclusions on its effectiveness for weight loss. There is no evidence of any harmful effects in humans.

Phaseolus vulgaris Phaseolus vulgaris, the common bean, is an herbaceous annual plant domesticated independently in ancient Mesoamerica and the Andes and now grown worldwide for its edible bean. Water extract of a common white bean has been shown in vitro to inhibit the digestive enzyme α-amylase and prevent starch absorption, which may lead to weight loss.178 Few clinical trials have shown beneficial effects of this bean on weight loss.179-181 One 4-week double-blind, placebo-controlled trial of 25 adults showed that white bean extract supplementation (2000 mg/d) led to significant decreases in body weight (6.0 lbs) and waist circumference (2.0 in.) compared with placebo, despite the finding that these individuals consumed more carbohydrates than control subjects.179 The same research group conducted another study of 50 obese participants and demonstrated that 3000 mg/d of the same extract led to a trend toward weight loss. Although clinical significance was not reached in this 8-week double-blind, placebo-controlled trial, the intervention group lost 3.79 lbs, whereas the placebo group lost 1.65 lbs.180 Celleno et al181 demonstrated that consumption of a supplement containing 445 mg of P vulgaris extract derived from white kidney beans had the potential to reduce weight, fat mass, and other measures of body composition in overweight individuals. Participants in this study consumed the supplement once a day before the main meal, which was rich in carbohydrate.181 Although these studies support the role of P vulgaris in weight loss with no reported adverse effects, further evidence is needed regarding potential gastrointestinal and other adverse effects.

Ginseng Ginseng has been used in traditional medicine for thousands of years and can be found in a number of plant species. Various ginseng extracts include Chinese or Korean ginseng (Panax ginseng), Siberian ginseng (Eleutherococcus senticosus), American ginseng (Panax quinquefolius), and Japanese ginseng (Panax japonicus). Different ginseng extracts are being studied for the treatment of many medical conditions, including weight control.182-185 Traditionally, the root of P ginseng has been used as a stimulant, and a few animal studies have suggested promise as a weight loss adjunct.182,186 In 1 study, extract from the P ginseng root produced significant weight- and fasting glucose-lowering effects in an obese, insulin-resistant rat model.186 Other species from the

Downloaded from ncp.sagepub.com at JOHNS HOPKINS UNIV on March 20, 2012

Nutraceutical Supplements for Weight Loss / Poddar et al 547

Ginseng family have shown similar activity. These actions can probably be attributed to the effect of several saponins as pancreatic lipase inhibitors.187 Saponins isolated from P japonicus rhizomes and fed to mice on a high-fat diet delayed the intestinal absorption of dietary fat by inhibiting pancreatic lipase activity.188 One study in patients with type 2 diabetes mellitus showed that ginseng therapy may have an effect on body weight.189 This double blind, placebo-controlled clinical trial showed that 200 mg of ginseng supplementation improved mood, improved fasting blood glucose levels, and reduced body weight among patients with type 2 diabetes mellitus.189 However, the placebo group also lost weight, indicating that ginseng may not be responsible for the effect seen in those from the intervention group.189 However, this study did not use body weight as a primary end point, and no other studies are yet available in humans. There are no documented adverse effects of ginseng.

have resulted in contradictory evidence. These supplements include conjugated linoleic acid, ginseng, glucomannan, green tea, HCA, L-carnitine, and psyllium. Although data on some supplements are encouraging, they may lack sufficient data or have been evaluated in poorly conducted clinical trials. Further studies are needed to evaluate the effectiveness of “herbal medicines” for weight loss and weight maintenance. Given the fact that conventional weight loss methods are not often effective long term, nonprescription dietary supplements have become popular among those seeking quick results. However, given the generally limited evidence of efficacy, even the smallest undesirable side effect of these supplements can shift the risk-benefit ratio to the unfavorable. Thus, in conclusion, based on the available science, recommending nonprescription dietary supplements as an adjunct to weight loss currently cannot be strongly recommended.

Conclusion

References

In summary, there is a dearth of data on the effect of dietary supplements on body weight loss in humans. The published data to date provide inconclusive evidence on the usefulness of different dietary supplements for weight loss. Caution must be exercised before recommending the use of these supplements for weight loss, as there is evidence that some may produce harmful effects. When using any of these alternative therapies as adjuncts for weight control, one must remember that, although derived from natural sources, they may nonetheless exhibit powerful pharmacologic effects and are thus still “medicines.” For example, foxglove, the plant origin of digitalis, has wellknown toxic effects comparable to those seen with pharmacologic digitalis dosing. Therefore, it is extremely important to use these supplements wisely and in limited amounts. In closing, it is fitting to highlight that perhaps the most general and safest alternative/herbal approach to weight control is to substitute low-energy density foods for high-energy density and processed foods, thereby reducing total energy intake.16-18 By taking advantage of the low-energy density and health-promoting effects of plant-based foods, one may be able to achieve weight loss, or at least assist weight maintenance without cutting down on the volume of food consumed or compromising its nutrient value. Because of the lack of quality, safety, and efficacy of many of the supplements discussed in this article, their use should generally be discouraged. Some supplements (eg, guar gum and chitosan) seem to show no efficacy. Ephedra, although quite effective for weight loss, is very well known for its adverse effects, and products containing even traces of this supplement should be discouraged. Many other supplements lack enough clinical evidence to support their role in weight loss, or studies